基于遥感影像的全球荒漠化指数构建及趋势分析

发布时间：2018-06-14 14:20

本文选题：荒漠化差值指数(DDI) + 时间序列趋势拟合分析　；参考：《电子科技大学》2015年硕士论文

【摘要】：根据联合国资料:全球约35%的土地处于沙漠化威胁中,每年约2000万hm2耕地沙化,粮食减产12%~21%,年损失260亿美元。日益加剧的荒漠化问题对生态环境、人类生活、社会经济等方面造成严重影响,对于荒漠化程度的监测以及荒漠化变化趋势的分析成为全球关注的热点。荒漠化现象在遥感影像上表现为裸露地表信息的增强和植被信息的减弱,可以采用地表反照率、地表温度、地表湿度、植被覆盖度等指标因子表征。因此本文以MODIS数据为主要数据源,对全球的荒漠化程度进行评价,并对其变化趋势进行分析。首先,本文采用荒漠化差值指数(DDI)评价全球荒漠化程度。该方法以归一化植被指数(NDVI)与地表反照率(Albedo)为监测指标,建立Albedo-NDVI特征空间,并利用Albedo和NDVI的负相关性,构建全球荒漠化差值指数(DDI)公式。在此基础上,完成2000~2014年全球DDI专题产品,并将该产品用于全球荒漠化程度的评价。其次,针对全球、各大洲、全国以及全国各省市等不同区域完成2000~2014年的荒漠化程度评价及荒漠化变化趋势分析。基于全球DDI专题产品,以分级图的形式,直观展现各区域的荒漠化状况;基于全球DDI数据,以像元为单位,通过时间序列趋势拟合分析法,完成2000~2014年的全球DDI变化趋势分布图,并对各区域的DDI变化趋势进行分析;基于各区域的年度DDI均值变化曲线,完成2000~2014年各区域的DDI数据对比分析。最后,通过全球环境监测指数(GEMI)与常用植被指数在植被覆盖情况上的监测效果,充分说明GEMI可用于全球的植被状况监测。一方面完成全球GEMI专题产品,并用以评价全球植被覆盖状况。另一方面,基于2000~2014年的GEMI与DDI的年度均值变化趋势,对比分析DDI的监测效果。论文结论:1、从2000到2014年,全球的植被覆盖程度下降,荒漠化问题加剧。2、全球的荒漠化分布与全球植被覆盖的分布情况基本一致。具体表现如下:(1)以常绿阔叶林为主的赤道附近,植被覆盖度高,DDI均值达1.45;(2)北美洲和亚洲的中高纬度地区主要植被类型是针叶林和落叶阔叶林,DDI均值在1.1~1.3左右,而北美洲东海岸和欧洲地区达到1.4;(3)各大洲近15年的DDI总体均值,从小到大,依次为:北美洲(0.70)、大洋洲(0.79)、非洲(0.96)、亚欧大陆(1.12)、南美洲(1.17)。
[Abstract]:According to the United Nations, about 35 percent of the world's land is under the threat of desertification. About 20 million hm2 of cultivated land is desertification each year, and the grain yield is reduced by 12% 21%, with an annual loss of $26 billion. The increasing problem of desertification has a serious impact on the ecological environment, human life, social economy and so on. The monitoring of the degree of desertification and the analysis of the trend of desertification have become the focus of global attention. The phenomenon of desertification in remote sensing images is characterized by the enhancement of bare surface information and the weakening of vegetation information, which can be characterized by surface albedo, surface temperature, surface humidity, vegetation coverage and so on. Therefore, using MODIS data as the main data source, the degree of desertification in the world is evaluated and the trend of desertification is analyzed. First of all, the desertification difference index DDI) is used to evaluate the degree of global desertification. In this method, the normalized vegetation index (NDVI) and surface albedo (Albedo) are used as monitoring indexes to establish the Albedo-NDVI feature space. Using the negative correlation of Albedo and NDVI, the global desertification difference index (DDI) formula is constructed. On this basis, the global DDI product is completed from 2000 to 2014, and the product is used to evaluate the degree of desertification in the world. Secondly, according to the different regions of the whole world, every continent, the whole country and the provinces and cities of the whole country, the evaluation of desertification degree and the analysis of the trend of desertification change from 2000 to 2014 are completed. Based on the global DDI thematic products, the desertification status of each region is visualized in the form of a hierarchical map. Based on the global DDI data, the trend distribution map of global DDI changes from 2000 to 2014 is completed through time series trend fitting analysis. Based on the annual DDI mean change curve of each region, the DDI data of each region from 2000 to 2014 are compared and analyzed. Finally, the global environmental monitoring index (GEMI) and the common vegetation index (GEMI) can be used to monitor vegetation status in the world. On the one hand, the global GEMI thematic products are completed and used to evaluate the global vegetation coverage. On the other hand, based on the trend of annual mean of GEMI and DDI from 2000 to 2014, the monitoring effect of DDI is analyzed. From 2000 to 2014, the degree of vegetation cover decreased and the problem of desertification increased. The global distribution of desertification was basically consistent with the distribution of global vegetation cover. The main vegetation types in the middle and high latitudes of North America and Asia are coniferous forests and deciduous broadleaved forests. The average DDI of each continent is from small to large in the last 15 years. The order of DDI is: North America 0.70, Oceania 0.79, Africa 0.96, Eurasia 1.12, South American 1.17.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X87;X171

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